Electron deficient polymers

Electron-Deficient Polymers — Luminescent Transport Layers... 

Electron-Deficient Polymers - Luminescent Transport Layers 16 Other Electron-Deficient PPV Derivatives 19 Electron-Deficient Aromatic Systems 19 Full Color Displays - The Search for Blue Emitters 21 Isolated Chromophores - Towards Blue Emission 21 Comb Polymers with Chromophores on the Side-Chain 22 Chiral PPV - Polarized Emission 23 Poly(thienylene vinylene)s —... 

In push pull polymer 77, both the absorption and emission maxima are red-shifted relative to 1. The LED performance of these materials appeared to be rather low (the EL efficiency of 0.002cd/A and the maximum luminance of 100cd/m2 was achieved at 30 V), and the turn-on voltage for the push-pull polymer 77 (4 V) was lower than that in more electron-deficient polymers 75 and 76. 

It was already established that pure ethyl-" " and f-butyllithium exist as six- and fourfold polymers, respectively, in benzene solution. Apparently, C—Li bond cleavage takes place in this solvent leading to an exchange of alkyl groups between polymeric organo-lithium molecules when both compounds are present. The products are believed to be electron-deficient polymers of the type (EtLi) (f-BuLi) , wha-e m is a small number such as 4 or 6. ... 

Furthermore, addition of electron acceptors as dopants may stabilize the coating material as they probably act as a source of electrons to augment surface oxidation. The dopants, in their reduced forms, are poised to donate electrons to the electron-deficient polymer or metal substrate. 

The only other compoimds R2M (M = Be or Mg) whose structure has been firmly established at the time of writing are Me2Be, Me2Mg, Et2Mg and Bu 2Be. The first three of these are electron-deficient polymers, and the metal atoms in the dimethyls are surrounded by four methyl groups in a nearly tetrahedral arrangement. 

Reactions between the lighter second group dialkyls, which are A type acceptors, and bases such as ethers and tertiary amines may be complicated both by steric factors and by heats of co-ordination sometimes being similar to heats of depolymerization of electron-deficient polymers. 

The criss-cross addition of azines of aromatic aldehydes with various electron-deficient olefins in which the double bond is terminal, for example, methyl acrylate, acrylonitrile, or in which allylic substituents do not sterically hinder the reaction, for example, maleic anhydride, is well known and was duly covered in CHEC-II(1996)<1996CHEC-II(8)747>, as well as in a review <1997ALD97>. Recently, the reaction has been used for the preparation of hyperbranched polymers <1998MI2655, 2002MAC712>. 

A more recent publication by Weigand and Pelka has disclosed a polymer-bound Buchwald-Hartwig amination [40], Activated, electron-deficient aryl halides were coupled with conventional PS Rink resin under microwave irradiation. Subsequent acidic cleavage afforded the desired aryl amines in moderate to good yields (Scheme 7.22). Commercially available Fmoc-protected Rink amide resin was suspended in 20% piperidine/N,N-dimethylformamide at room temperature for 30 min to achieve deprotection. After washing and drying, the resin was placed in a silylated microwave vessel and suspended in dimethoxyethane (DME)/tert-butanol... 

The details of how nitroaromatic explosive molecules interact with the chromo-phores in the polymer matrix requires further study. Initial observations suggest that because nitroaromatic explosive molecules are highly electron-deficient, that chro-mophores have an electron-rich donor and bridge, and that both nitroaromatic explosives and chromophores are highly polar, explosive molecules and chromo-phores have a strong tendency to interact with each other. The interaction between explosives and the polymer takes place in two steps. In the initial step nitroaromatic explosive molecules create a more polar environment around the chromophores. The increased polar environment produces a solvatochromic red-shift of the... 

Burn and coworkers [173] synthesized copolymer 143, containing a similar electron deficient moiety (triazole) incorporated in the PPV backbone. They have reported an efficient blue emission from this polymer (APL = 466 nm (solution), 486 nm (film), PL = 33% (film)) although the efficiency of the PLED fabricated as ITO/PPV/143/A1 was not very high (CT>j ) reached 0.08% at a luminance of 250 cd/m2). 

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